Categories of road signs

There are four categories of road sign in Australia:

regulatory signs

warning signs

guide signs

truck noise advisory signs.

Regulatory signs

Regulatory signs instruct road users of their legal obligations - eg speed limits, prohibited or permitted movements at intersections, and parking controls. Most are rectangular with a black legend on a white background.

Exceptions to this include:

stop signs (octagonal)

give way and roundabout signs (triangular)

speed restriction signs (symbol enclosed in a red circle)

no right hand turn signs (red slash to indicate the prohibition of a movement)

prohibitive parking signs (red legend on a white background)

permitted parking signs (green legend on a white background).

Warning signs

Warning signs indicate hazards that may not be obvious to the approaching driver. They are a diamond shape with a black legend or symbol on a yellow background to indicate caution.

Warning signs include:

advisory speed signs (to negotiate bends safely)

advance warning of traffic control devices (such as traffic lights)

road conditions (eg slippery when wet).

Guide signs

Guide signs inform motorists of:

routes

direction and distance to destinations

points of interest and roadside facilities.

Truck noise advisory signs

Noisy engine brakes are a common complaint. Truck noise advisory signs remind truck drivers to avoid using their exhaust brakes around metropolitan and country areas.

Use of engine brakes has become a normal driving habit but is unnecessary in most situations and especially in flat residential areas.

Road signs and placement

The type and placement of road signs is very important and carefully considered. For signs to be effective they need to:

command attention

make meaning clear at a glance

allow adequate response time.

Signs and other traffic devices lose effectiveness if used unnecessarily or too frequently, so their use is restricted to the minimum consistent with safety requirements.